Harifidy Ranaivomanana

Permeability Prediction of Soils Including Degree of Compaction and Microstructure

AbstractThe present paper deals with the proposition of an original analytical permeability model of compacted soils. The model involves the microstructure of the material through the porosity and the pore-size distribution obtained by mercury intrusion porosimetry (MIP), as well as the degree of compaction. Their effects on the morphological parameters of the porous network (tortuosity and interconnection of pore network) are studied. The model was developed and tested on various types of soil: a loamy sand, a gravelous sand, a clay, and an alterite. Samples were compacted with various degrees of compaction: 85, 95, 100, and 105% of the optimum dry density as determined by a standard compaction method. The experimental results obtained for both loamy and gravelous sands and for clay were well reproduced by the model, except for the alterite. Such results might be explained by the high brittleness of the alterite, leading to a crumbling phenomenon rather than to its densification during the compaction pro...

Modelling the mechanical strength development of treated fine sediments: a statistical approach

ABSTRACT Sediments valorization (recycling) has revealed limitations due to different restrains and practical difficulties. When it comes to different recovery methods, the possibility of valuing diverse types of sediments still needs to be defined. Using a statistical approach, the present study aims to quantitatively estimate the mechanical resistance of stabilized sediments. A database that included 22 fine sediments is selected and assembled from the literature. These sediments were treated with distinct types and quantities of additives (fillers and/or binders). The present study includes two parts. On one hand, using multivariate linear regression tool of XLstat software, an analytical model that highlights the effects of various parameters influencing the mechanical resistance of treated sediments after 28 days is obtained. This model showed that organic matter content and plasticity index are the most significant factors of sediments characteristics, while cement is the best mechanical strength booster. On the other hand, the evolution of treated sediments mechanical resistance over time is modelled by an exponential relationship using a least square regression method. Both models showed acceptable accuracies compared to a panel of selected experimental values.